package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

@Component
public class RedisIdWorker {
    /**
     * 开始时间戳
     */
    private static final long BEGIN_TIMESTAMP = 1640995200L;
    private static final String KEY_PREFIX = "order:";
    private static final int COUNT_BITS = 32;
    private StringRedisTemplate stringRedisTemplate;

    public RedisIdWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    /**
     * 生成订单id
     *
     * @param keyPrefix 工作机器id
     * @return 订单id
     */

    public long nextId(String keyPrefix) {
        // 获取当前日期
        LocalDateTime now = LocalDateTime.now();
        //保证生成的 ID 从项目开始时间计数，而不是从 1970 年开始
        long nowSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = nowSecond - BEGIN_TIMESTAMP;
        // 拼接key
        String date = now.format(DateTimeFormatter.ofPattern("yyyyMMdd"));
        // 生成自增值
        Long increment = stringRedisTemplate.opsForValue().increment("icr:"+KEY_PREFIX + date);
        // 拼接并返回
        return timestamp << COUNT_BITS | increment;
    }
}
